1. Field of the Invention
The invention relates to a semiconductor lamp, more particularly to a multi-color semiconductor lamp and to a method of providing colored illumination.
2. Description of the Related Art
Semiconductor devices that are capable of generating different colored light outputs are known in the art. Examples of such semiconductor devices of the prior art are those disclosed in the following U.S. patents:
U.S. Pat. Nos. 3,875,456, 3,890,170, 5,491,349, 5,752,766 and 5,812,105 disclose various forms of semiconductor devices that comprise a plurality of light emitting diodes disposed close to one another and respectively emitting light of different colors. The light emitting diodes can be individually controlled to operate solely or in combination, thereby resulting in different colored light outputs. It is noted that the semiconductor devices disclosed in these patents require a relatively complicated control circuit for controlling the differently colored light emitting diodes individually in order to generate a wide range of different colored light outputs.
Semiconductor devices that are capable of generating light outputs of multiple wavelengths are also known in the art. Examples of such semiconductor devices of the prior art are those disclosed in the following U.S. patents:
U.S. Pat. No. 5,077,588 discloses a semiconductor device operable to emit an infrared light and a visible light. U.S. Pat. No. 5,585,648 discloses a semiconductor device capable of emitting light in the green to ultraviolet spectrum. While the light outputs of the semiconductor devices disclosed in these patents are of multiple wavelengths, they are insufficient to generate a wide range of different colored light outputs.
In addition, semiconductor devices that are capable of generating white light are also known in the art. Examples of such semiconductor devices of the prior art are those disclosed in the following U.S. patents:
U.S. Pat. No. 5,684,309 discloses a light emitting diode that includes stacked active layers of indium gallium nitride separated by barrier layers of aluminum gallium nitride or aluminum indium gallium nitride. U.S. Pat. No. 5,743,629 discloses an illumination system in which nonwhite light from a light emitting diode is reflected by a reflector to obtain white light. While the devices disclosed in these patents can be designed to generate light of a particular color, they are not designed for providing multi-color illumination.